Introduction
During recent years we have often shared road crash reports where road users crashed into guardrails and road barriers.
In some incidents, we witnessed rather horrific injuries, and these often create questions regarding these traffic safety systems.
How much thought and planning are behind erecting these guardrails and how do they make our roads safer?
We decided to approach the South African National Roads Agency to gain some insights on guardrails and roadside barriers.
How would we best describe or define a guard rail?
Guardrails form part a larger system known as traffic safety barriers or vehicle restraint systems. Vehicle restraint systems are systems intended to stop or re-direct a vehicle that is leaving the roadway and it is utilized to shield road users from potential hazards alongside the travelled way and should be able to redirect or contain:
- An errant vehicle without imposing intolerable vehicle occupant forces;
- Vehicles in a range of sizes, weights and designs; or
- An errant vehicle over a range of impact speeds and impact angles.
What are the basic components of a guardrail?
A Guardrail can be split into three basic components namely the base, used to fix the Guardrail to the ground, the post which is used as a linking mechanism and finally the Steel beam.
The system most commonly used on South African roads is the steel “W” beam guardrail and comprises wooden posts “fixed” into the soil with steel “W” beams attached.
Do factors such as the potential resulting damage and severity of injury in a road crash play a role in how a guardrail is erected?
It is important to note that there are several factors that should be considered in determining the appropriate vehicle restraint system.
Do SANRAL and other road authorities have to follow specific [internationals] standards in the placement and the construction of guard rails?
SANRAL’s road design guide is based on AASHTO standards. The broader context in which guardrail placement exists is known as Geometric Engineering, these engineers rely on guidelines and standards.
The American Association of State Highway and Transportation Officials (AASHTO) is a standard-setting body which publishes specifications, test protocols and guidelines which are used in highway design and construction throughout the United States.
Are there specific reasons that may cause road authorities not to place guard rails in specific areas or locations?
SANRAL road design guidelines are based on old AASHTO standards.
Do crimes such as theft or damage to property have a negative impact on guard rails and safety on South African roads?
In short Yes, whilst roads authorities do their utmost to ensure the safety and well-being of road users instances such as theft and destruction have negative impacts on those using the roadway.
What does SANRAL do to address and reduce the impact of theft and destruction of guard rails?
SANRAL has appointed service providers responsible for the maintenance of the road infrastructure who regularly travel the road network. It is their duty and responsibility to ensure that guardrails are in working order.
In the event of a road crash caused by lawless driving such as drunk driving would Sanral have mechanisms in place to claim damages from the lawless road user?
There are mechanisms in place to claim damages on damages on certain infrastructure components.
What are the average costs to replace and repair a guardrail? What would determine the costs – the length of rail, components needed, reflective materials etc?
Approximately R800/m to install and R800/m to replace.
What are major threats to the incorrect and unsafe construction and placement of guard rails?
Incorrect placement and construction of guardrails can result in guardrails becoming a hazard to road users.
Where can the public report unsafe guard rails?
The public’s first point of contact would generally be with the service providers maintaining the route, ie the route manager, (their numbers are available on various information boards along the route), alternatively contact SANRAL directly, details are on the website at www.nra.co.za
Are guardrails erected only to protect from the side of the driver on the road service or would it also be intended to keep animals and pedestrians from entering traffic from the side of the road?
Primarily yes, it is installed as a vehicle restraint system and sometimes a pedestrian protection system.
How would the construction of guardrails in high-risk areas/high accidents zones differ from guard rails on the open roads?
I would say that this question relates more to traffic safety barriers, there exist numerous products that can be used for different circumstances. It is the role of the Roads Authority to ensure that the appropriate traffic safety barrier suits its operational requirements.
Would guard rails at bridges require specific have different requirements than on the open road?
Yes, guardrails or vehicle restraint systems should be designed for the applicable environmental conditions, traffic, traffic mix, speeds etc.
Do SANRAL and local and provincial traffic authorities share best practices with regards to the construction guard rails?
Yes, this occurs in the form of standard specifications and guidelines that are adopted by various authorities.
Any other aspects that are important for the public to know which are not addressed in the above questions
Report incidents where guardrails or other vehicle restraint systems are damaged to the responsible road authorities.
Also view:
The South African National Roads Agency